The document defines different types of energy including mechanical energy, which is energy due to position or movement, and non-mechanical energy. It provides equations for kinetic energy and potential energy. Work is defined as force applied over a distance in the direction of motion. The work-energy principle states that work done equals the change in kinetic and potential energy. Energy is always conserved but can be transferred or transformed between different forms. Forces can be conservative, where work depends only on start and end points, or non-conservative where work depends on the path taken and may generate heat or sound. Power is defined as the rate at which work is done or energy is expended.

1. Work, Energy and PowerWork, Energy and Power
KineticKinetic (work)(work) potentialpotential

2. *Energy – Types**Energy – Types*
 *Mechanical Energy*Mechanical Energy: Energy due to: Energy due to
position in a field force or energy due toposition in a field force or energy due to
movementmovement
 *Non-mechanical Energy*Non-mechanical Energy: Energy that: Energy that
does not fall into the above categorydoes not fall into the above category

3. *Energy – Flow Chart*Energy – Flow Chart
Energy
Mechanical Non-mechanical
Electromagnetic
Sound
HeatKinetic Potential
Linear
Rotational
Gravitational
Elastic
Electric
Magnetic
Chemical
Nuclear

4. *Kinetic Energy Equation*Kinetic Energy Equation
2
2
1
mvKE =

5. *Potential Energy Equation*Potential Energy Equation
mghPEg =

6. *Work – Energy Principle*Work – Energy Principle oror workwork
done by a net forcedone by a net force oror net work donenet work done
on an objecton an object
KEdFW netnet ∆==

7. Energy ConservationEnergy Conservation
 *The total energy is neither increased nor*The total energy is neither increased nor
decreased in any process.*decreased in any process.*
 Energy can, however, be transformed from oneEnergy can, however, be transformed from one
type to another AND transferred from onetype to another AND transferred from one
body to another, BUT, the total amount ofbody to another, BUT, the total amount of
energy in the process remains CONSTANT!energy in the process remains CONSTANT!

8. Conservative and NonconservativeConservative and Nonconservative
ForcesForces
 Conservative Force:Conservative Force: A force such that the workA force such that the work
done on an object by the forcedone on an object by the force does notdoes not depend on thedepend on the
path taken, rather it depends only on the initial andpath taken, rather it depends only on the initial and
final positions (gravitational, elastic, electric)final positions (gravitational, elastic, electric)
 Nonconservative Force:Nonconservative Force: A force such that the workA force such that the work
done on the object by the forcedone on the object by the force doesdoes depend on thedepend on the
path taken (friction, air resistance, rocket propulsion).path taken (friction, air resistance, rocket propulsion).
A lot of times these forces generate heat or soundA lot of times these forces generate heat or sound
which are non-mechanical energies.which are non-mechanical energies.

9. Work – Energy PrincipleWork – Energy Principle
RedefinedRedefined
 So if energy is conserved we canSo if energy is conserved we can
write it this way using mechanicalwrite it this way using mechanical
and non-mechanical energiesand non-mechanical energies
NCWPEKE =∆+∆

10. Work – Energy Principle &Work – Energy Principle &
Mechanical Energy ConservationMechanical Energy Conservation
 If we ignore nonconservative forces (frictionIf we ignore nonconservative forces (friction
and the such), the implication is that no non-and the such), the implication is that no non-
mechanical energies are present (heat, sound,mechanical energies are present (heat, sound,
light, etc) therefore…light, etc) therefore…
0=∆+∆ PEKE

11. Mechanical Energy ConservationMechanical Energy Conservation
21 EE =

12. Mechanical Energy Conservation withMechanical Energy Conservation with
energy lostenergy lost
friction
lost
WEE
EEE
+=
+=
21
21

13. *Kinetic and potential energy*Kinetic and potential energy
convert to one another*convert to one another*
Frictionless Coaster : Total = Mechanical Energy

14. Work and PowerWork and Power
 *Work*Work – done when a force acts on an object in– done when a force acts on an object in
the direction the object moves*the direction the object moves*
 *Requires Motion and Force in one direction!**Requires Motion and Force in one direction!*
 Man is not actually doing work whenMan is not actually doing work when
holding barbell above his headholding barbell above his head
 Force is applied to barbellForce is applied to barbell
 If no movement, no work doneIf no movement, no work done
He does work
They do no
work

15. Work Depends on Direction Continued…Work Depends on Direction Continued…
A.A. *Force and Motion in the same direction*Force and Motion in the same direction
B.B. **The horizontal component of the force does work.The horizontal component of the force does work.
C.C. **The vertical force does no work on the suitcase.The vertical force does no work on the suitcase.
Force
This force
does work
This force
does no
work
Force
Direction of motion Direction of motion Direction of motion
*Work and Power**Work and Power*

16. *Work**Work*
 Most of the time F is in the direction of dMost of the time F is in the direction of d so…so…
 Work is done by a force acting on aWork is done by a force acting on a
body!body!
 Symbol: WSymbol: W
 Unit : J, jouleUnit : J, joule
 1 J = 1 Nm1 J = 1 Nm
FdW =max

17. *Work**Work**The amount of work a force does on an object is magnitude of the force
times the distance over which it’s applied*:
W = F x
*This formula applies when:
• the force is constant
• the force is in the same direction as the displacement of the object
F
x
Symbol: WSymbol: W
Unit : J, jouleUnit : J, joule
1 J = 1 Nm1 J = 1 Nm

18. *Power**Power*
*Power is defined as the rate at which work is done. It can also
refer to the rate at which energy is expended or absorbed.
Mathematically, power is given by:
P = W
t